Topic
Shielded metal arc welding
About: Shielded metal arc welding is a research topic. Over the lifetime, 4462 publications have been published within this topic receiving 40560 citations. The topic is also known as: manual metal arc welding & flux shielded arc welding.
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54 citations
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TL;DR: Although mass emission is low for tungsten inert gas welding and resistance spot welding, due to the low particle size of the fume, these processes cannot be labeled as toxicologically irrelevant and should be further investigated.
Abstract: Studies in the field of environmental epidemiology indicate that for the adverse effect of inhaled particles not only particle mass is crucial but also particle size is. Ultrafine particles with diameters below 100 nm are of special interest since these particles have high surface area to mass ratio and have properties which differ from those of larger particles. In this paper, particle size distributions of various welding and joining techniques were measured close to the welding process using a fast mobility particle sizer (FMPS). It turned out that welding processes with high mass emission rates (manual metal arc welding, metal active gas welding, metal inert gas welding, metal inert gas soldering, and laser welding) show mainly agglomerated particles with diameters above 100 nm and only few particles in the size range below 50 nm (10 to 15%). Welding processes with low mass emission rates (tungsten inert gas welding and resistance spot welding) emit predominantly ultrafine particles with diameters well below 100 nm. This finding can be explained by considerably faster agglomeration processes in welding processes with high mass emission rates. Although mass emission is low for tungsten inert gas welding and resistance spot welding, due to the low particle size of the fume, these processes cannot be labeled as toxicologically irrelevant and should be further investigated.
54 citations
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TL;DR: In this paper, a welding procedure based on using two-pass laser scans is introduced for joining overlapped galvanized high-strength steel sheets, where the first pass is based on a defocused laser spot that scans across the top of the overlapped sheets and heats the zinc coating at the faying surface to be melted and vaporized, while the second pass is executed with a focused laser spot to perform the welding.
53 citations
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TL;DR: In this article, an empirical relationship to predict tensile strength of pulsed current gas tungsten arc welded AZ31B magnesium alloy joints was developed, incorporating process parameters such as peak current, base current, pulse frequency and pulse on time.
53 citations
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TL;DR: In this paper, the authors developed a unified arc electrode model that enables them to make predictions of the time development of molten drops from the welding wire in gas metal arc welding, where the wire is taken as the positive electrode, and the effects of surface tension, magnetic pinch forces, and convection within the drop are taken into account to predict drop detachment for any given arc current.
Abstract: We have developed a unified arc electrode model that enables us to make predictions of the time development of molten drops from the welding wire in gas metal arc welding. The wire is taken as the positive electrode, and the effects of surface tension, magnetic pinch forces, and convection within the drop are taken into account to predict drop detachment for any given arc current. For pure argon, we have previously predicted the sharp transition that is observed experimentally at about 300 A between globular transfer at low current, when drop diameters are larger than the wire diameter, and spray transfer, for currents above 300 A, when drop diameters are smaller than the wire diameter. In this paper, we predict that addition of 25% of CO/sub 2/ to the argon leads to an increase in the transition current to more than 325 A, also in agreement with published experimental results. For pure CO/sub 2/, we find a significantly different drop behavior due to the more constricted arc. Both small and large drops are produced, with many very small drops being produced successively between each large drop.
53 citations